Electrologica X1

from Wikipedia, the free encyclopedia

The Electrologica X1 (or simply EL X1) was a digital computer designed in the Netherlands and produced from 1958 to 1965. About 30 systems were built and also sold abroad.

development

The X1 was designed in the Mathematisch Centrum Amsterdam by Carel Scholten and Bram Loopstra . The X1 was produced by Electrologica NV , a company that was founded specifically for this purpose by the Mathematisch Centrum and the insurance company Nillmij in 1958.

commitment

One system was sold to a coffee company in Germany, from where, on the initiative of Horst Herrmann , it came to the TU Braunschweig as a used machine in 1962 , where it was in use until 1975 (the machines retained a certain coffee smell until the end). There was a slightly larger system that could be fed with punched tape, punched card or magnetic tape and that was only operated by professional operators or by trained users, as well as a smaller one that was only equipped with punched tape (input and output) and an electric typewriter ran in self-service by the students. They were programmed almost exclusively in Algol 60 .

construction

The X1 was a fully transistorized binary computer with a ring core memory . The circuits were designed as plug-in modules in metal cups about the size of a cigarette packet. In discrete transistor logic, a module contained a single logic gate, usually one or two transistors . The CPU was a cube-shaped cabinet about one cubic meter in volume.

The word length of the memory was 27 bits. A smaller machine had about 7 Kwords of these, which filled a second cabinet the same size as the CPU. A maximum of 32,768 memory locations could be addressed because 15 address bits were available.

The "small X1" could use approx. 3 kByte of memory directly, with a "split compiler" 8 kByte; the "big X1" could use 16 kByte memory.

Punched tapes , punched cards , magnetic tape , line printers , DIN A1 plotters and electric typewriters were available as peripherals . The X1 was one of the first European computers with an interrupt system. Building on this, the interfaces to peripheral devices could be implemented much more efficiently, so that they mainly offered a certain buffer between fast CPU and slow peripheral, like an output channel of later mainframe computers.

As with the competing models Zuse Z22 and the ZEBRA could all commands, not just the branches conditionally ( conditional ) are executed. This made particularly compact written programs possible. The following example shows the loading of the absolute amount of the memory value from memory location n into Accumulator A : 

   2A n P  // [n] nach A kopieren
 N 3A n    // wenn A negativ ist, kopiere -[n] nach A

A remarkable peculiarity of the X1, or at least the people who worked with it, was the use of 32-bit notation in its own base 32-digit representation for the addresses.

The X1 was the subject of Edsger W. Dijkstra's doctoral thesis and the target machine for the first fully implemented Algol-60 compiler , completed by Dijkstra and Jaap Zonneveld. In 1965 the X1 was replaced by the X8. Electrologica was acquired by Philips the following year .

photos

The following pictures (except for the last one) were taken shortly before and after the X1 of the TU Braunschweig was demolished in 1975.

  • X1 console. In the plastic drawers are the punched tape rolls from Checker, two Algol 60 compilers and various tools, on the right two discs of the punched tape winding mechanism (hand-operated).

  • X1 backplane with wiring after demolition

  • X1 modules after demolition, repositioned

  • X1 modules after demolition, the color indicates the type of logic gate in the module

  • Inner workings of an X1 module

  • IBM typewriter of the type that could be connected to the X1 as an output unit in a similar version (without keys)

credentials

  • Edsger W. Dijkstra: Communication with an Automatic Computer. Dissertation . University of Amsterdam, 1959.

Individual evidence

  1. ^ Jörg Munzel: The development of computer science at the TU Braunschweig. In: W. Kertz (Ed.): Technical University of Braunschweig: from the Collegium Carolinum to the Technical University. Olms, Hildesheim 1995, pp. 701-709.

Web links

Commons : Electrologica X1  - collection of images, videos and audio files